Approaches and methods

Micrographs and SSU and LSU rDNA PCR products of isolated single cells

The approach in TaxMArc is to combine molecular methods and bioinformatics with high-resolution microscopy and taxonomy to analyse recent and historic (up to 100 years old) samples. 

TaxMArc collaborates closely with the MicroPolar project (2014-2017) that aimed at “Describing the structure, function and diversity of the microbial community in Arctic waters during a full annual cycle” using metabarcoding and metagenomics. During the MicroPolar cruises, cultures have been isolated and samples have been collected for morphological studies using light microscopy (LM) as well as scanning (SEM) and transmission electron microscopy (TEM). The analyses of these samples in the frame of TaxMArc will allow for the naming and description of protist species and linking the morphology of the cultured organisms to their genetic signature.

TaxMArc also collaborates with the Roscoff Culture Collection (CNRS, France), which contains more than 200 strains isolated from the Arctic Canada and W Greenland as well as projects coordinated by Alfred Wegener Institute for Polar and Marine Research (Germany) studying the biodiversity and distribution of marine protists in the Atlantic Arctic, including East Greenland. Finally, the available samples, cultures and environmental data will be expanded during cruises planned by Norwegian partners (IMR, NPI and UNIS) and by the Norwegian project Nansen Legacy (2018-2022). Further, historical samples from cruises by Nansen and Amundsen, and from Hasle’s plankton collection will be examined to reveal changes over the last century.

The information gained from metabarcoding, flow cytometry and low resolution LM during previous projects will be combined with our detailed morphological data from high-resolution LM and EM of natural samples and cultures. This will allow us to identify and quantify more protists to lower taxonomical levels than what has been possible so far.

At present, molecular analyses of protist diversity are hampered by a limited number of reference DNA-sequences. TaxMArc will provide reference nucleotide sequences to be included in curated nucleotide databases, such as PR2, EukRef and UniEuk and curate these databases further, linking the genetic diversity to morphological species. This will provide a necessary tool in future monitoring and research based on DNA-sequences. 

The available environmental sequence and read data will be used to assess the geographical distribution of the Arctic. Further, by integrating molecular, microscopic and environmental data from MicroPolar and other similar projects in the consortium we will assess under which environmental conditions specific taxa or community compositions occur and how the community composition and structure vary through the season. Based on obtained results we will publish the first web-based flora/fauna of marine Pan-Arctic protists.